In order to filter the air flowing through an intake line of an internal combustion engine of a motor vehicle, it is known to use filter elements which are inserted in an air filter box mounted in the intake line. The air filter elements are constructed essentially as hollow cylinders with a continuous interior cavity. The filter box is constructed such that the air flows laterally against the outer cover of the filter element, passes through the air-permeable filter element, and escapes to the filter box outlet through the interior cavity. A further line section is connected downstream from the filter box outlet, in which, for example, an air-flow meter is fitted.
However, the lateral direction of the air at the outer cover of the filter element causes a highly uneven air flow through the filter element, which varies according to construction. Experience has shown that most of the air charged with dust and other particles flows through a section of the filter element facing away from the filter box outlet, causing this section to become heavily clogged over time, so that the air then flows through other parts of the filter element. Because of the uneven flow through the filter element, a highly asymmetrical flow profile forms initially in the interior cavity, which then changes significantly over time. This asymmetrical flow profile, which changes over time, is transferred in the main direction of flow to the line section fitted with the air-flow meter and connected to the filter box outlet. The change in the flow profile causes a disadvantageous drift of the sensor characteristic curve of a sensor element situated in the air-flow meter.